The Doctor and Sarah arrive back in the TARDIS to find London completely deserted - except for the dinosaurs. Has the return of these prehistoric creatures been deliberately planned and, if so, who can behind it all?
 

Three hundred and fifty million years ago, dinosaurs crawled the Earth, devouring everything in sight. But then they disappeared. Certainly, no one ever expected them to return... 

When Doctor Who lands in London and finds the entire city deserted - except for dinosaurs - he figures something really weird is going on. It is. A clever group of misguided idealists is at the center of a bizarre plot to reverse Time to a golden era - an era before technology, before pollution, before the hydrogen bomb. The group is going to give the human race a second chance. But, to implement Operation Golden Age, the past must be eliminated. The present will not exist - and only the chosen will survive. Doctor Who must turn the clock forward to stop Operation Golden Age, but will he be able to do it before Earth's Time runs out?